Paul Bird

Objective In early rheumatoid arthritis (RA), longitudinal studies have demonstrated that magnetic resonance imaging (MRI) is more sensitive than radiography in demonstrating progressive erosive joint damage. The present study evaluated the progression of erosive damage in patients with established RA by using limited field of view MRI and comparing the results with those obtained by radiography. Methods MRI and radiographic studies were available from 47 of 60 patients enrolled in a 2‐year RA observational study. MRI of the metacarpophalangeal (MCP) joints was performed at baseline and 2 years later, and a single observer scored all of the MR images with the use of an MRI scoring method developed by the Outcome Measures in Rheumatology Clinical Trials MRI RA study group. MR images from 14 patients were reread by the same observer after 1 week to assess intraobserver reliability. Radiographs were obtained at baseline and at 2 years, and were scored by an observer using the Scott modification of the Larsen score. Radiographs from 14 patients were reread after 1 week to assess the intraobserver reliability. The smallest detectable difference (SDD) was calculated for the MRI scores, the total Larsen scores, and the Larsen scores of the dominant‐hand MCP joints (MCPs 2–5) for direct comparison with the MRI results. Results The median disease duration was 5.1 years (range 0.5–29 years). Evidence of erosion progression was identified by MRI in 30 patients (64%). The SDD based on the intraobserver scores was calculated as ±3.25 units. Using this result, 11 patients (23%) showed evidence of erosion progression on MRI that was greater than the SDD. The SDD for progression based on the intraobserver total Larsen radiographic scores was 0.77 units, and the SDD for the Larsen scores of the dominant‐hand MCP joints was 1.55 units. On the basis of these results, radiographic progression was noted in 19 patients (40%) by the total Larsen score and 7 patients (15%) by the dominant‐hand MCP Larsen score. The most striking finding was that although MRI and radiograph scores identified a similar group of patients as having progression of joint damage, the radiographs of both hands appeared to be more responsive to change, albeit with the caveat that radiographic progression was most marked outside the dominant‐hand MCP joints. Conclusion There was no clear advantage of MRI with a limited field of view as compared with radiographic imaging of both hands in detecting progression of joint damage over 2 years in this group of patients with established RA. The conclusion drawn from this study is not that radiographs are better than MRI or vice versa, but that careful analysis is required to determine the optimal imaging method, or combination of imaging methods, for each study population, depending on the objective and duration of the study.

Scoring erosions on magnetic resonance imaging (MRI) is one method of estimating damage in patients with rheumatoid arthritis (RA), but it has limitations. The aim of this pilot study was to assess the feasibility and inter-reader reliability of computer assisted erosion volume estimation in patients with RA. Intra-reader and inter-occasion reliability was also assessed, and different slice thicknesses were compared in terms of erosion volume estimation. A 3 mm slice thickness 3D gradient-echo sequence followed by a 1 mm sequence was performed at baseline and repeated within 24 h with metacarpophalangeal (MCP) joints 2 to 5 of the dominant hand included in the field of view. Three readers were instructed to grade MCP 2 and 3 using the OMERACT grading system and then to measure the erosion volume of the same joints using OSIRIS software. The inter-reader reliability of the grading method and the volume method was calculated, as well as the inter-occasion reliability, by comparing results from each reader from baseline to the followup scan. One reader performed repeat volume measurements on 5 patients to assess the intra-reader reliability. Five patients were included in the study. Expressed in terms of intraclass correlation coefficients (ICC), the inter-reader and inter-occasion reliability of the volume method were comparable to the existing OMERACT scoring system, but large systematic differences in volume estimations were found between readers. The intra-reader reliability was excellent. Good correlation was demonstrated between the total erosion scores and the total erosion volumes. For both erosion volumes and erosion scores, 1 mm and 3 mm acquisitions produced variable results between readers, with no clear pattern of underestimation or overestimation for either slice thickness. The volume estimation method was more time consuming, taking roughly 5 times as long as the scoring method. Computerized MRI erosion volume measurements are feasible, with high intra-observer and inter-occasion reliabilities. Despite high ICC, the inter-observer reliability is not sufficient for multicenter use without prior reader training and calibration. The optimal slice thickness was not determined.

Objective: One of the major aims of therapy in rheumatoid arthritis (RA) is to prevent erosive disease and subsequent disability. One of the important goals of therapy assessment must therefore be the accurate measurement of damage progression. We undertook this study to assess the feasibility, reliability, and validity of measuring magnetic resonance imaging (MRI) erosion volumes and synovial volumes in the wrists of RA patients with the use of a semiautomated computerized method.Methods: Twelve subjects with seropositive RA were chosen to reflect a spectrum of RA severity as determined by the clinical Joint Alignment and Motion (JAM) Scale. MRI of the dominant wrist was performed at the same time of day at baseline and at 48 hours. Images were transferred to a workstation. Erosion volumes and synovial volumes were measured on the coronal images using OSIRIS imaging software. All images were reread in random order at 72 hours by 1 observer. The results were compared with erosion scores and global synovitis scores obtained by the same observer using the Outcome Measures in Rheumatology Clinical Trials MRI RA scoring system. Radiographs were performed at baseline and were read on 2 occasions by 1 observer using the Scott modification of the Larsen method.Results: Total erosion volume per subject ranged from 0 cm³ to 4.7 cm³. The total synovial membrane volume per subject ranged from 0.1 mm³ to 12.1 cm³. Intraclass correlation coefficients for erosion volumes and synovial volumes demonstrated excellent intraobserver reliability and interoccasion reliability. There was a strong positive correlation between the total erosion volume and the total erosion score. The correlation between the synovial volumes and synovitis score was less favorable (r = 0.53–0.86). Positive correlations were demonstrated between the erosion volumes, the JAM score, and the modified Larsen scores. No significant correlation was demonstrated between the erythrocyte sedimentation rate, C‐reactive protein level, swollen joint count, tender joint count, or the Disease Activity Score in 28 swollen and 28 tender joints and the synovial volumes or synovitis scores.Conclusion: This study is the first to demonstrate the feasibility, reliability, and validity of computerized MRI erosion volume measurements in the wrists of RA patients. The method will require further evaluation in terms of interobserver reliability, with examination of responsiveness in longitudinal studies, but the method demonstrates excellent interoccasion and intraobserver reliability and compares favorably with existing RA clinical outcome measures. Synovial volume measurements demonstrated good intraobserver reliability and appeared to be more responsive to synovial change over a 48‐hour period in this group of patients.